This application is related to Japanese Patent Application No. 2001-077704 filed on Mar. 19, 2001, and No. 2002-008482 filed on Jan. 17, 2002, based on which this application claims priority under the Paris Convention and the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to data recording methods and apparatus for recording frame data according to motion JPEG or the like onto a recording medium, data reproducing methods and apparatus for reproducing the frame data from the recording medium, and recording media recording thereon frame data according to motion JPEG or the like.
2. Description of the Related Art
In various standards for static images, JPEG (Joint Photographic Coding Experts Group) is widely used in particular. JPEG is a standard for compression and expansion of color static images, regulated by ITU-TS (International Telecommunication Union-Telecommunication Standardization Sector; formerly the CCITT) and ISO (International Organization for Standardization).
On the other hand, as standards for dynamic images known are MPEG (Moving Picture Image Coding Experts Group), motion JPEG, and so on.
Motion JPEG is a standard in which the technique of JPEG is applied to dynamic images. In motion JPEG, data of each frame of a dynamic image is provided according to JPEG. A data reproducing apparatus rapidly expands the data of the frames in series to realize a dynamic image display.
More specifically, a recording medium records thereon data of static images of frames that constitute a dynamic image, for example, as illustrated in FIG. 1, the frame data indicated by xe2x80x9c0x00xe2x80x9d, xe2x80x9c0x01xe2x80x9d, xe2x80x9c0x02xe2x80x9d, xe2x80x9c0x03xe2x80x9d, xe2x80x9c0x04xe2x80x9d, . . . , being recorded in this order. The data reproducing apparatus reproduces the static images in order as streaming data from the recording medium to realize a dynamic image display. FIG. 1 illustrates a case of a normal-speed play.
In motion JPEG, each frame is constituted by entire data of a static image, differently from MPEG in which only information on difference between frames is used. Therefore, editing at an arbitrary part, a reverse play, a multiple-speed play, etc., can be realized in simple manners.
In the case of reproducing a dynamic image from a recording medium such as an optical disk on which frame data according to motion JPEG are recorded, a special reproduction method, e.g., the below-described first or second reproduction method, is required for realizing a double-speed play, a quadruple-speed play, or the like, (hereinafter referred to as a high-speed play). The case of a double-speed play of an optical disk will be described below by way of example.
In the first reproduction method, frame data recorded on an optical disk according to the order of xe2x80x9c0x00xe2x80x9d, xe2x80x9c0x01xe2x80x9d, xe2x80x9c0x02xe2x80x9d, xe2x80x9c0x03xe2x80x9d, xe2x80x9c0x04xe2x80x9d, . . . xe2x80x9c0x07xe2x80x9d, as illustrated in FIG. 1, are read out in order and then stored in a buffer memory or the like. After this, only data of even frames (xe2x80x9c0x00xe2x80x9d, xe2x80x9c0x02xe2x80x9d, xe2x80x9c0x04xe2x80x9d, xe2x80x9c0x06xe2x80x9d, . . . ) of the stored frame data are read out to be expanded.
In the second reproduction method, when frame data are read out from the optical disk on which the frame data is recorded according to the order of xe2x80x9c0x00xe2x80x9d, xe2x80x9c0x01xe2x80x9d, xe2x80x9c0x02xe2x80x9d, xe2x80x9c0x03xe2x80x9d, xe2x80x9c0x04xe2x80x9d, . . . xe2x80x9c0x07xe2x80x9d, only data of even frames (xe2x80x9c0x00xe2x80x9d, xe2x80x9c0x02xe2x80x9d, xe2x80x9c0x04xe2x80x9d, xe2x80x9c0x06xe2x80x9d, . . . ) are read out with skipping data of odd frames (xe2x80x9c0x01xe2x80x9d, xe2x80x9c0x03xe2x80x9d, xe2x80x9c0x05xe2x80x9d, xe2x80x9c0x07xe2x80x9d, . . . ), as illustrated in FIG. 2, and then the read-out data of even frames are expanded.
In the case of the first reproduction method, however, the data reproducing apparatus, i.e., an optical disk player, can not realize any high play speed more than its data read performance. Any optical disk player has a limit of its data read performance (data read speed). The play speed is restricted by the limit of the data read performance of the optical disk player even if the player has its CPU capable of realizing a higher-speed play.
In case of the second reproduction method, when the optical disk player reads out data from an optical disk, the data skipping operation and the data read operation must frequently be switched over from one to the other. Such frequent switchover operations require excessive time and may cause a bottleneck on the high-speed play. In particular, the frequent switchover operations may cause an excessive load on the reading head unit (an optical pickup) of the optical disk player. The higher the play speed is, the more rapidly the optical disk player must perform the switchover operations. This makes the optical disk player difficult to realize the higher-speed play.
An object of the present invention is to provide data recording methods and apparatus, data reproducing methods and apparatus, and recording media, all of which are capable of realizing such a high-speed play as were more than the data read performance of the data reproducing apparatus, and realizing a high-speed play with eliminating wasteful operations and relieving the load on the reading head unit of the data reproducing apparatus.
According to an aspect of the present invention, n-bit codes are assigned respectively to 2n frame data in the order of a normal-speed play, the bit order of each of the n-bit codes is reversed, a recording order of the frame data is defined based on the reversed n-bit codes, and then the frame data are recorded in the defined recording order onto a recording medium. According to another aspect of the present invention, when frame data are reproduced from the recording medium, frame data corresponding in number to the reciprocal of the multiple in a desired play speed are read out in order from the recording medium, the read-out frame data are stored in a buffer memory or the like, and then the stored frame data are read out from the buffer memory or the like in a predetermined order in accordance with the desired play speed.
In the present invention, the recording order of the frame data on the recording medium is devised so that all the frame data need not be read out in a high-speed play of the recording medium and only the necessary frame data can be reproduced even without frequent skip operations upon reproduction.
In this manner, a data reproducing apparatus can realize such a high-speed play as were more than its data read performance, wasteful operations in a high-speed play can be eliminated, and the load on the reading head unit of the data reproducing apparatus can be relieved.
Other and further objects and features of the present invention will become obvious upon understanding of the illustrative embodiments about to be described in connection with the accompanying drawings or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employing the invention in practice.